The homopolymer of 7, oxa-bicyclo(2,2,1)heptane and of its alkyl-derivatives is known and is described in the technical literature. This homopolymer, although showing a crystallinity at X-rays, is poorly soluble in most common solvents, and suffers from the drawback that it has a melting temperature (generally higher than 350.degree. C.) which is higher than its decomposition temperature. This set of properties makes the homopolymer not very interesting from an industrial viewpoint, due to the moulding difficulties.